This invention relates to an electromagnetic device and, more particularly, to an electromagnetic device such as, for example, a solenoid-operated actuator appropriate for an automatic player incorporated in an automatic player keyboard musical instrument.
An automatic player piano is a typical example of the automatic player keyboard musical instrument. The automatic player piano is the combination of an acoustic piano and the automatic player. The automatic player is broken down into an array of solenoid-operated key actuators and a controller. The array of solenoid-operated key actuator is mounted on a key bed, and is located under the rear portion of the keyboard. The controller sequentially interprets music data codes representative of a tune previously performed, and selectively supplies driving signals to the soleniod-operated key actuators. Then, the solenoid-operated key actuators sequentially project the plungers, and the plungers upwardly push the rear portions of the black/white keys. The black/white keys are sequentially moved without a fingering, and actuate the associated action mechanisms. The hammers are driven for rotation by the associated action mechanisms, and the hammers strike the associated sets of strings. Then, the sets of strings vibrate so as to generate acoustic piano tones alone, the tune. The gap between the key bed and the keyboard is so narrow that the manufacturer makes an effort to scale down the solenoid-operated key actuators without reduction of the electromagnetic force.
If the acoustic player piano is of the type controlling the plungers through a feedback loop, the plungers are associated with plunger sensors, respectively, and the plunger sensors supply feedback signals representative of the current velocity of the plungers to the controller. The controller estimates trajectories of the projecting plungers, and regulates the driving signals for controlling the plunger velocity. The plunger sensor is, by way of example, implemented by the combination of a magnet piece and a solenoid. The magnet piece is attached to the plunger, and is movable inside of the solenoid. While the magnetic piece is moving inside of the solenoid, current is electromagnetically generated. The feedback signal is produced from the current. Thus, the solenoid-operated key actuators are indispensable components of the automatic player and, accordingly, the acoustic player keyboard musical instrument.
FIG. 1 illustrates the prior art solenoid-operated key actuator. The prior art solenoid-operated key actuator comprises a solenoid and a plunger (not shown). T he solenoid is broken down into following p arts. Collars and a cylindrical body form a bobbin 1. The collars are attached to both ends of the cylindrical body, and an insulated wire 2 is wound on the cylindrical body. The insulated wire 1 is covered with insulating tape 3, and both end portions of the insulated wire 2 are taken out through the insulating tape 3. A lead mount 5 is adhered to the insulating tape 3, and lead wires 4 are soldered to the insulated wire 2 on the lead mount 5.
Another prior art solenoid is different in coupling structure from the above-described prior art solenoid. Conductive terminals are fixed to both ends of the insulated wire, and the lead wires are connected to the conductive terminals. The junctions between the conductive terminals and the lead wires are inserted into heat shrinkable tubes, and, thereafter, head is applied to the heat shrinkable tubes. Then, the tubes are shrunk, and the junctions are tightly wrapped in the tubes.
Problems are encountered in the two kinds of prior art solenoids as follows. First, the prior art solenoid of the type having the insulated wire 2 soldered on the lead mount 5 is bulky and costly. The problems are reasoned as follows. As described hereinbefore, the manufacturer has been making the effort to scale down the solenoid-operated key actuator without reduction in electromagnetic force. The electromagnetic force is varied with the number of turns of the insulated wire 2. In other words, the manufacturer does not want to reduce the number of turns, and the insulated wire 2 occupies basic space around the bobbin 1. The prior art soleniod-operated key actuator shown in FIG. 1 further requires additional space around the basic space, because the insulating tape 3 is wound on the insulated wire 2 and the lead mount 5 is adhered to the insulating tape 3. The insulating tape 3 and the lead mount 5 increase the volume of the prior art solenoid, and the makes the prior art solenoid-operated key actuator bulky. The soldering step is required for the connection between the insulated wire 2 and the lead wires 4. The soldering is usually carried out by an assembling worker. The assembling worker is expected to solder the extremely small parts, i.e., the end portions of the insulated wire 2 and the lead wires 4. The soldering requires close attention, and a large amount of time and labor is consumed for the soldering. The production cost is increased due to the low throughput, and the prior art solenoid-operated key actuator is costly. Thus, the insulating tape 3 and the lead mount 5 makes the prior art solenoid bulky, and the soldering increases the production cost.
The prior art solenoid-operated key actuator of the type using the heat shrinkable tubes is also bulky and costly. The shrunk tube is less reliable, and an insulating sheet is required between the tube and a yoke for perfect electrical isolation. This results in that the bulky prior art solenoid. Moreover, a large amount of time and labor is consumed in the insertion of the junctions into the heat shrinkable tubes and the application of heat. The throughput is low, and the production cost is increased. This results in the bulky and costly solenoid.
It is therefore an important object of the present invention to provide an electromagnetic device, which is compact and low in production cost.
It is also an important object of the present invention to provide an automatic player, which is equipped with the electromagnetic devices for an automatic performance without fingering.
It is another important object of the present invention to provide an automatic player keyboard musical instrument, in which the automatic player is installed for performing a tune on the keyboard without fingering.
In accordance with one aspect of the present invention, there is provided an electromagnetic device comprising a solenoid including a body formed of a non-magnetic material for providing a magnetic path to a magnetic field and having a closed curved surface, a first surface outside of a space around the closed curved surface and a second surface outside of the space and the first surface, conductive pins partially embedded in the body and having respective first end portions projecting from the first surface and respective second end portions projecting from the second surface and a coil formed on the closed curved surface so as to occupy the space and having both end portions electrically connected to the first end portions, respectively, an electric connector including a socket holder associated with the conductive pins and having a guard portion for preventing the first end portions and the second end portions from damage and a socket connected to a cable, coupled to and separated from the socket holder and having holes, and a member electromagnetically influenced in the magnetic field so as to give rise to relative motion between the solenoid and the member, wherein the second end portions of the conductive pins are inserted into the holes so as to be electrically connected to the cable when the socket is coupled to the socket holder.
In accordance with another aspect of the present invention, there is provided an automatic player for selectively actuating plural manipulators comprising plural solenoid-operated actuators respectively associated with the plural manipulators for actuating the associated manipulators, respectively, each of the plural solenoid-operated actuators including a solenoid including a body formed of a non-magnetic material for providing a magnetic path to a magnetic field and having a closed curved surface, a first surface outside of a space around the closed curved surface and a second surface outside of the space and the first surface, conductive pins partially embedded in the body and having respective first end portions projecting from the first surface and respective second end portions projecting from the second surface and a coil formed on the closed curved surface so as to occupy the space, having both end portions electrically connected to the first end portions, respectively and creating the magnetic field when electric current flows therethrough and a movable member associated with one of the plural manipulators and moved in the magnetic field for actuating the associated one of the plural manipulators, plural electric connectors respectively associated with the plural solenoid-operated actuators and each including a socket holder having a guard portion for preventing the first end portions and the second end portions from damage, and a socket connected to a cable, coupled to and separated from the socket holder and having holes, the second end portions of the conductive pins being inserted into the holes so as to be electrically connected to the cable when the socket is coupled to the socket holder, and a controlling system respectively connected through the cables to the plural electric connectors, and selectively supplying the current to the solenoids of the plural solenoid-operated actuators for actuating the associated manipulators with the movable members.
In accordance with yet another aspect of the present invention, there is provided an automatic playing keyboard musical instrument comprising plural keys independently moved for producing tones, and an automatic player including plural solenoid-operated key actuators respectively associated with the plural keys for actuating the associated keys, respectively, each of the plural solenoid-operated actuators including a solenoid including a body formed of a non-magnetic material for providing a magnetic path to a magnetic field and having a closed curved surface, a first surface outside of a space around the closed curved surface and a second surface outside of the space and the first surface, conductive pins partially embedded in the body and having respective first end portions projecting from the first surface and respective second end portions projecting from the second surface and a coil formed on the closed curved surface so as to occupy the space, having both end portions electrically connected to the first end portions, respectively and creating the magnetic field when electric current flows therethrough and a movable member associated with one of the plural manipulators and moved in the magnetic field for actuating the associated one of the plural manipulators, plural electric connectors respectively associated with the plural soleniod-operated key actuators, each of the plural electric connectors including a socket holder having a guard portion for preventing the first end portions and the second end portions from damage and a socket connected to a cable, coupled to and separated from the socket holder and having holes, the second end portions of the conductive pins being inserted into the holes so as to be electrically connected to the cable when the socket is coupled to the socket holder and a controlling system connected through the cables to the plural electric connectors and selectively supplying the current to the solenoids of the plural soleniod-operated actuators for actuating the associated keys with the movable members.